Toa P-924A Instruction Manual

Operation Instruction Manual
TOA 900 SERIES
POWER AMPLIFIER P-924A
1 Wide frequency response; 20 — 20,000 Hz, ±1dB
2 Low distortion and noise level
3 Excellent output regulation
4 A full range of plug-in modules
5 Self-protecting circuitry design
6 Varied output impedances; 4 and 8 ohms, 25 and 70 volts
7 Input level switch (selectable 1,000mV/100mV)
8 Portable or rack-mounting type
The TOA P-924A Power Amplifier delivers up to 240 watts of power
at less than 0.5% total harmonic distortion (THD) from 20 to
20,000 Hz (transformerless 4-ohm output). The P-924A has a high-
impedance direct input and an input port (edge connector) to
accept one module accessory. Module selection is determined by
application among the TOA plug-in modules:
The M-01 series, M-03 series, M-51 series and M-61 series Micro-
phone Preamplifiers, R-01 Mag. Phono Preamplifier, the U-01 series,
U-21 series and U-61 series Auxiliary Preamplifiers for high-level
sources, the B-01 series Bridging Transformers for bridging high-
impedance lines, the L-01 series Line Matching Transformers for
matching 600-ohm lines, and the S-01, S-02 and S-03 Tone signal
generators for generating attention-getting signals and 1 KHz sine
wave for testing within the total system.
The P-924A has a low-cut switch for cutoff frequency of 60 Hz, and
an input-level switch for input sensitivity of 1V (0dBv) or 100mV
(—20dBv). Output terminals provide connections for 4-ohm and
8-ohm speakers, plus 25-volt and 70-volt speaker distribution
outlets.
With plug-in modules, the TOA P-924A Power Amplifier may be
used as a pre/power amplifier.
The P-924A can be rack mounted by using the MB-931A Rack-
mounting Bracket accessory. The PF-911 Perforated Panel (1.73
inches, 1 rack unit) accessory provides suitable ventilation, finished
in color to match the P-924A.
133-02-907-70
Printed in Japan
ToaElectricCo.,Ltd.
KOBE, JAPAN
Features General Descriptions

Item
1
2
3
4
5
Name
POWER
ON-OFF
SWITCH
METER
INPUT
VOLUME
CONTROL
PROTECTION
INDICATOR
(RED)
NORMAL
INDICATOR
(GREEN)
Function/Description
Applies line power. Two-position
pushbutton switch for on-off modes.
Indicates the output level of the
amplifier. At rated output, it shows
0 VU (at continuous sine-wave
signal input).
When power is turned on, meter
illuminates.
Adjust gain of INPUT.
out in about 5 seconds after the power
switch is turned on.
If the LED indicator remains lit
indicating that a muting relay is not
activated, turn the power switch off
after disconnecting the speaker line
and turn it on again. As a result,
1. if the LED indicator goes out in
about 5 seconds, the speaker line
may be short-circuited or
overloaded.
Check the speaker line.
2. unless the LED indicator still goes
out, abnormality has occurred in the
power amplifier stage.
Check the power amplifier stage.
Lights up when the amplifier is
normally working.
Item
1
2
3
4
5
6
7
8
9
10
11
Name
AC POWER
SUPPLY
CORD
AC OUTLET
(Unswitched)
AC FUSE
DC FUSE (-)
DC FUSE (+)
OUTPUT
TERMINALS
MODULE
INPUT
PORT
LOW-CUT
SWITCH
INPUT
LEVEL
SWITCH
DIRECT
INPUT
TERMINAL
EARTH
TERMINAL
Function/Description
Connectsto powersource.
Provides AC powerforauxiliaryequip-
ment with power consumption of up to
500W.
Protectsamplifierfrom excessivecurrent
drain. Replace only with same type fuse.
Refer to qualified service personnel if
fuse blows repeatedly.
AC FUSE 250V 7A
DC FUSE (-) 250V 8A
DC FUSE (+) 250V 8A
Connect to speakers.
Accepts PLUG-IN MODULESwhichare
optionally available. Module selection is
determined by application.
Cuts off unnecessary low frequency.
Selects input sensitivity. Place in "1V
(0dBv)" position when normally used
asa power amplifier.
Note: The position of INPUT-LEVEL
SWITCHshould bechangedaccording to
modules used or equipment connected to
DIRECT INPUT TERMINAL.
Connects directly to external equipment
without using modules. Unbalanced
10k ohms.
Normallyconnects to a record player's
ground.
Front Panel Controls and Features
Rear Panel Controls and Features
This LED indicator comes on and goes
— 1 —

• Two types of input terminals are provided on the rear for input
connections.
(1) 2P terminal (marked HOT, E)
It is provided for direct input (unbalanced, 10k ohms) without
using plug-in modules. This terminal is directly connected with
a potentiometer inside.
(2) Plug-in module input
Select the desired modules according to application.
Plug the module into INPUT PORT, slid-
ing it between the guide rails, and secure
with two screws.
When INPUT PORT is not occupied, cover
the PORT with the blank panel, and
secure it with screws.
Be sure that INPUT-LEVEL SWITCH is in
the proper position for the modules used
or the equipment connected to DIRECT
INPUT TERMINAL.
When the P-924A is used in combination
with a mixer preamplifier or serves as an
incremental power amplifier, normally
place INPUT LEVEL SWITCH in "1V
(0dBv)" position.
Place the LOW-CUT
SWITCH in "CUT" position
When connecting speakers to the 4
25V and 70V via the output
transformer (matching transformer) and direct output of 4
the
connecting method differs in each case. See the following diagrams.
Note: Impedances indicated below imply total speaker system
(load) impedance.
When connecting speakers to any one of the outputs of 8
25V
or 70V (BALANCED TRANSFORMER OUTPUT);
The speaker outputs of the amplifier are 4
8
25V and 70V.
Connect speakers to one of these outputs.
Class 2 wiring may be used.
Since these outputs consist of 8
<P-924A>
output. (UNBLANCED
Signal tone generator module
(with presettable output level control)
B-01
L-01
S-01
S-02
S-03
1kHzSineWave
Yelp and buzzer
One-tone chime and
continuousone-tone
chime
*See PLUG-IN MODULES for detail.
Plug-in Modules
Plug-in Modules and Input Level SW Setting
Model
No.
Input level SW
Setting
1V
(0dBV)
100mV
(—20dBV)
Balanced low impedance microphone preamp. module
(with presettable low-cut filter, high-cut filter and gain
controls)
Unbalanced high impedance microphone preamp module
(with presettable low-cut filter, high-cut filter and gain
controls)
Equalized mag phono preamp module
(with presettable gain control)
Unbalanced high impedance auxiliary preamp. module
(with presettable gain control)
—
RemoteVolume
control
Voice Gate
Compressor
-
-
—
RemoteVolume
control
Compressor
M-61
M-03
R-01
Balanced 10k bridging transformer module
Balanced 600
bridging transformer module
DIRECT OUTPUT);
<P-924A>
Input Connections
Output Connections P-924A
Note:
In this case, the LOW-CUT SWITCH should be "CUT" posi-
tion. This amplifier is characteristically flat even in the low fre-
quency range. Therefore, in TRANS OUTPUT, the acoustic
effect and frequency-response characteristics may be altered.
In TRANS OUTPUT, cut off unnecessary low frequency to ob-
tain the best acoustic condition.
— 2 —

Do not block cover ventilation holes.
The amplifier should not be placed in areas;
1. with poor ventilation
2. exposed to direct sunlight.
3. with high ambient temperature or adjacent to heat-generating
equipment.
4. with high humidity or dusty levels.
5. susceptible to vibration.
To mount the amplifier in a standard 19-inch equipment rack, use
theMB-931A Rack-mountingBracketaccessory.
Remove 4 screws securing case.
When all connections are completed, turn power switch on. Then,
the meter is illuminated. Approx. 5 seconds after switching power
on, the amplifier comes into operation.
ADJUSTMENT OF VOLUME CONTROL
Adjust the input volume control to obtain appropriate output level.
In normal use of BGM playing or announcement, the deflection of
the meter is recommended to be within the range as indicated in the
drawing. Tone quality will be considerably deteriorated if the
pointer indicates around 0 VU.
Fix the MB-931A with attached 4 screws.
MB-931A The length of the screws should not
(Silver) exceed 12mm (1/2 inches).
(OPTION)
Perforated Panel
PF-911 (OPTION)
(Silver)
If two or more amplifiers are mounted in
an equipment rack, space should be pro-
vided between the units for ventilation.
The PF-911 Perforated Panel is recom-
mended for this purpose.
In normal use of BGM
playingorannouncement.
The pointer of meter indicates 0 VU if continuous signals like sine
waves are applied to the input of the amplifier.
Continuous signals
When the power amplifier is used in combination with a mixer pre-
amplifier, adjust the total gain at the mixer preamplifier with the
gain setting of the power amplifier at maximum.
•
Unpacking
Upon receipt of the amplifier shipment, please inspect for any
damage incurred in transit. If damage is found, please notify your
local TOA representative and the transportation company
immediately.
State date, nature of damage, whether any damage was noticed on
the shipping container, prior to unpacking. Please give waybill
number of shipping order.
•
Failure
Should amplifier fail, contact your nearest TOA authorized con-
tractor or service center.
Installation
Rack Mounting
Operation
Servicing
— 3 —

Type
Output
Power Band Width
Frequency Response
Total Harmonic Distortion
inputs
Input
Sensitivity/Impedance
Outputs
(D) = Direct
(T) = Transformer
Output Regulation (1 kHz)
Signal to Noise Ratio
(Band
Pass
20 —
20,000
Hz)
Controls
Indicator
Protection
P-924A
Power amplifier
(D) 240W RMS
(T) 220W RMS
(D)20-20,000 Hz,0.5% THD
(T) 50-20,000 Hz,0.5% THD
(D) 20
-20,000
Hz,±1
dB
(T) 2 0- 15,000 Hz,±1 dB
(T ) 20 -20,000 Hz ,-3dB
0.01% at 1 kHz, rated output
One Input Port : Port accepts any input module except T-01 , which cannot be used.
One Direct Input Note : Use of direct input prohibits use of modular input port.
Input Port : 100 mV or 1 ,000 mV (Switchable)/10k ohms
Direct Input : 100 mV or 1 ,000 mV (Switchable)/10k ohms
Main (T): 8 ohms, 25 & 70 volts, balanced
Main (D): 4 ohms, unbalanced
(D) Less than 0.5 dB, no load to full load (T) Less than 1 .0 dB, no load to full load
Input level switch in 0 dBv (1 ,000 mV) position : 105 dB
Input level switch in —20 dBv (100 mV) position : 90 dB
1 Input gain control
1 Input level switch
1 Power ON/OFF switch
1 Low-cut switch (60 Hz, 6 dB/octave)
1 Illuminated VU meter, 2 LED for protection circuit
Self-protection, with 2 AC fuses (1 inside) and 2 DC fuses
Specifications are subject to change without notice.
Connectors
Power Consumption
Temperature Range
Dimensions in mm (inches)
(high) x (wide) x (deep)
Weight (without input modules)
Color_______________
Other Features
Inputs
Output
ACoutput
AC power cord/plut
Card-edge connector and screw-terminal strip
Screw-terminalstrip
3-pin grounding type
SJT, 3-prong type
AC 120 volts, 60 Hz, 3A
-10°C to +60°C (12°F to 140°F)
150.5 (5.92") x 420 (16.54") x 333 (13.11")
Rack-mounting space size "3U" (5.21")
19.5kg (43 Ibs.)
Silver
Output disconnected for approx. 5 sec. after switching power on.
P-924A
Block Diagram P-924A
Specifications
— 4—

(OPTION)
MODEL
Connection
Balanced Connection
PLUG-CONNECTION
Unbalanced Connection
Input,OutputConnection Input, OutputConnection
M-01 series M-11
M-51 series M-21
M-61 series
B-01 Series B-11, L-01
Series L-11, L-41, T-01
U-01 series U-12
U-11 series
M-03
R-01
U-21
U-61 T-02
CANNON XLR-3-12 (Male) type CANNON XLR-3-12 (Male) type
XLR-3-11 (Female) type
CANNON
XLR-3-11 (Female) type
Phone Plug (Double Pole) Phone Plug (Single Pole)
RCA Phono Jack
The TOA PLUG-IN MODULES are suitable for TOA 900 SERIES MIXER
POWER AMPLIFIERS A-901A, A-903A, A-906A, and A-912A MIXER
PREAMPLIFIER M-900A, POWER AMPLIFIERS P-906A, P-912A, P-
924A, and IN-WALL AMPLIFIERS W-906A, W-912A. Owing to wide
selection of types of connectors can also meet the needs of equipment
to be connected. MICROPHONE PREAMPLIFIER M-01 series, M-51
series, M-61 series, M-03, M-11 and M-21 incorporates controls for
high-cut, low-cut and gain. A gain cotrol is built in MAG. PHONO
PREAMPLIFIERS R-01, and AUXILIARY PREAMPLIFIERS U-01 series,
U-11 series, U-12, U-21 and U-61, LINE OUTPUT T-01 and AUX INPUT-
LINE OUTPUT T-02.
M-61 and U-61 are built-in compressor circuit to protect the output
level from distortion as a result of excessive input and keeps it con-
stant.
M-51 series is built-in voice gate circuit to be automatically activated by
presence of signal.
U-12 can adjust mute level.
T-01 series is an output module with transformer, serving as a line out-
put for recording, etc...
A group of special signal generating modules is also available for
catching-attention before announcement and testing within the total
systems. ALL PLUG-IN MODULES have handles on their front for easy
insertion and removal.
FEATURES
1. Wide dynamic range
2. Low noise and distortion
3. Wide frequency response
4. Built-in remote volume control circuit (M-21)
5. Built-in remote master volume or remote volume control circuit. (U-21)
6. Built-in muting circuit to mute incoming signal when MUTE TERMINAL
is grounded, (available for modules having 10's in its model number
such as U-11.)
7. Built in muting circuit to deliver or mute its output signal when MUTE
TERMINAL is grounded. (M-11)
8. Built-in signal activated muting function (L-41)
9. Presettable gain control (except for B-01, B-11, L-01 and L-11)
10. Microphone modules furnished with tone controls (M-01, M-11, M-21,
M-51, M-61, and M-03)
11. Built-in voice gate circuit (to be activated by input signals.) (M-51 series.)
12. All the microphone modules (except M-03) come with phantom power-
ing capability.
13. Built-in compressor circuit (M-61, U-61)
14. Built-in variable muting circuit to adjust the muting level. (U-12)
CANNON
Plug-in Modules
— 5 —

TOA900SERIES
Applications
Module
Types
Source
Impedance
inputSensitivity
forRatedOutput
(100mV)
Specifications
GAIN
Connector
Max.Befor eClip
into10k-ohm stoad
aslessthan0,5%THD
(1kHz)
outpu tvoltag e
S-01,S-02,S-03
Frequency
Response
±1dB
Noiselevel
equivalen t
inputnois e
orS/N
Signal
Level
Remotevolume
controlrange
Use10Kohms
potentiometer
Compress.
Range
[Threshold ]
Power
Requirement
[24V
DC]
Controls
[Presettable
]
Weight
(max.)
FRONTPANELCONTROLSANDFEATURES
Moduleswithbuilt-incontrolsareprovidedinthefollowingsixtypes.
—6 —
GAINCONTROL
THRESHOLD
(M-61)
OUTPUTGAIN
(T-02)
NOMINALPOSITION
MARK
LOW-CUTFILTER
CONTROL
330Hz,6dB/oct
(max.attenuation)
MUTELEVEL
(U-12)
INPUTGAIN
(T-02)
Thisadjustsgam.Turnclockwise(CW)to
increaseandcounter-clockwise(CCW)to
reducegam
Setthegamaslowaspossible,thereby,
noisecanbereduced,andthemaximum
permissibleinputlevelisraised.
Thisadjuststhresholdlevelofcompressor.
Turnclockwise(CW)toreducethreshold
level(toactivatethecompressorwithlow-
erinputsignallevel).
Thisadjustsgamofthelineoutput.Turn
clockwise(CW)toincreaseandcounterc-
lockwise(CCW)toreducegamregardless
ofsettingpositionoftheinputgamadjust
knob.Theleftfigureshowsnominalset-
tingofcontrols.
ThisprovidesflatcharacteristicsatfullCW
positionandattenuationinlowfrequency
byturningCCW.Adjustittoobtainproper
tonequality.Withlow-cut,tonebecomes
clear.
Thisadjustsmutelevel.Turnclockwise
(CW)toincreasemutelevel(tobemuted
excessively)andcounterclockwise(CCW)
toreducemutelevel.
ThisadjustsinputgamfromAUX.Turn
clockwise(CW)toincreasegamandcoun-
terclockwise(CCW)toreduce.
—7 —
HIGH-CUTFILTER
CONTROL
4.2kHz,6dB/oct
(max.attenuation)
SENSITIVITY
(M-51)
ThisprovidesflatcharacteristicsatfullCW
positionandattenuationinhighfrequency
byturningCCW.Adjustittoobtainproper
tonequality.Withhigh-cut,tonebecomes
soft.
Thisadjustssensitivityforvoicegate.Turn
clockwise(CW)toincreasesensitivity(to
openthegateatfullCWpositionregard-
lessofanyinputlevel)andcounterclock-
wise(CCW)toreducesensitivity.
SPECIFICATIONSINCOMMON
Loadimpedance10k-ohms
MountingCard-edgeconnector
Dimensionsinmm(inches)78(3.07)x35(1.38)x88(3.46)
(H)x (W)x (D)
Plug-inModules

"JumperWireSetting"
M-01, 11,21,51,61
Allthemicrophonemodulescomewithphantompoweringcapability.I
notdesired,cutJ1ontheboard.
U-21
CutJ2ontheboardtouseasa remotemastervolumecontrolunit
LeaveJ2ontouseasa remote-controlAUXmodule.
U-61
CutJ2ontheboardtouseasa compressorunitwhichgoesbetween
PREAMPOUTandPOWERAMPIN(LINKIN/OUT).
M-11
Either(both)J3or(and)J4is(are)tobecutfora properoperation.
Refertothetablebelow.
^Z:ImpedanceMute:Normally"On",becomes"Off"whenmuting
__terminalsareclosed.
Mute:Normally"Off",becomes"On"whenmuting
terminalsareclosed.
(Plug-inModules)
S-01(1,000HzSINEWAVE)
CONNECTIONSItisoperatedbyclosingtheremote
switch.
Remoteswitch
S-02(YELPANDBUZZER)
CONNECTIONS
Yelpsignal
Remoteswitch
Buzzersignal
Eachsignalisgeneratedbyclosingcor-
respondingremoteswitches.
Remoteswitch
S-03(ONE-TONECHIMEANDCONTINUOUSONE-TONE
CHIME)
CONNECTIONS
One-tonechime
Remoteswitch
Byclosingtheremoteswitch,chime
soundsonce.
Continuousone-tonechime
Remoteswitch
Byclosingtheremoteswitch,one-tone
chimesoundscontinuouslyduringthe
closureoftheswitch.
Rack-mountingBracketsPerforatedPanel
(Silver)(Silver)VolumeControlCover
J3
on
cut
on
cut
J4
on
on
cut
cut
Function
Nooutputsignal
Normally"Off",becomes"On"whenmuting
terminalsareclosed.
Normally"On",becomes"Off"whenmuting
terminalsareclosed.
Worksasa regularmicrophoneinputmodule.
Plug-inModules
OperationandConnectionsBlockDiagrams(Plug-inModules)
Accessories
TOA900SERIES

— 10 —